The extensive use of plastic tubing has presented vexatious problems in the provision of a satisfactory union or separable coupling kit interconnecting aligned lengths of metal and plastic tubing, or two sections of plastic tubing. Quite effective solutions have been found under low pressure conditions, but these are quite unsuitable and quite unreliable for pressures in excess of 50 to 60 psi.
Typical examples of prior coupling proposals are disclosed in the following patents: Harkenrider U.S. Pat. No. 2,776,151; Houghton U.S. Pat. No. 2,998,269; Jewell U.S. Pat. No. 3,061,339; Richardson U.S. Pat. No. 3,264,013; Marcus et al U.S. Pat. No. 3,284,110; Gajewski et al U.S. Pat. No. 3,456,965; Garrett U.S. Pat. No. 3,565,468; Hollingsworth U.S. Pat. No. 3,801,141; Horsley U.S. Pat. No. 3,813,116; Taylor U.S. Pat. No. 3,837,683; Read U.S. Pat. No. 3,572,773; Lowe U.S. Pat. No. 4,026,584; and Carter U.S. Pat. No. 3,784,239. These disclosures represent a wide variety of concepts dealing specifically with junctions between tubing including at least one plastic tube. However, none of these proposals provide a satisfactory solution to the problem of separably joining two plastic tubes interconnecting closely spaced appliances and subject to higher fluid pressures, such as those in the range of 50 psi to 125 psi, or more. There are many operating environments subject to these pressure conditions as well as those including semi-permanently installed appliances inter-connected by plastic tubing with bonded joints. Service operations on such appliances frequently require severing the plastic tubing and this presents time consuming problems when re-joining the severed tubing. No satisfactory coupling meeting these and similar needs is presently available.